We present a computationally efficient relativistic formulation of the equation-of-motion coupled-cluster (EOM-CC) method for the double electron attachment (DEA) problem. In this work, the exact two-component Hamiltonian within the atomic mean-field approximation is employed, yielding results that are in close agreement with the corresponding four-component calculations. However, canonical DEA-EOM-CCSD calculations become prohibitively expensive for heavy elements and large basis sets due to the substantial memory requirements associated with the complex-valued 3p1h excitation manifold. To address this limitation, we introduce a new state-specific frozen natural spinor basis that significantly reduces the virtual space through two controllable truncation thresholds. Furthermore, the use of Cholesky decomposition for the two-electron integrals provides an additional reduction in memory requirements. The performance of the proposed approach is demonstrated through calculations of double ionization potentials and excitation energies for group-12 and group-14 heavy elements. Vertical excitation energies for heavy chalcogen dimers are also presented. In addition, a range of diatomic spectroscopic constants is evaluated for group-13 hydrides. Finally, the method is applied to predict the singlet-triplet gaps of dihalocarbenes, indicating that an accurate description of these systems may require excitation manifolds beyond the 3p1h space.
Double Electron Attachment and Double Ionization Potential Equation-of-Motion Coupled-Cluster Approaches with Full and Active-Space Treatments of 4-Particle-2-Hole and 4-Hole-2-Particle Excitations and Three-Body Clusters
Dissociative electron attachment to the H2O molecule. I. Complex-valued potential-energy surfaces for the 2B1, 2A1, and 2B2 metastable states of the water anion
我们提出的计算结果定义全球，三维表示的复值势能面的双峰B1，双峰A1，和双峰B2亚稳态的水阴离子的物理过程的基础上的解离电子附着到水。共振能量的实部由在限制的希尔伯特空间中进行的构型相互作用计算获得，而能量的虚部（宽度）由复杂的Kohn散射计算获得。由于在2A1和2B2表面之间存在圆锥形相交，因此在2A1和2B2表面上进行diabatization。我们讨论的影响，构造的势能面的形状将有后的核动力学的解离电子附着到水。这项工作最初出现在Phys Rev A 75，012710（2007）中。已在此处更正了出版版本中的排版错误。
A Low Cost Relativistic Algebraic Diagrammatic Construction Method Based on Cholesky Decomposition and Frozen Natural Spinors for Electronic Ionization, Attachment and Excitation Energy Problem
Equation-of-Motion Coupled-Cluster Theory based on the 4-component Dirac-Coulomb(-Gaunt) Hamiltonian. Energies for single electron detachment, attachment and electronically excited states
本文采用四分量相对论哈密顿量的单双耦合团簇运动方程（EOM-CCSD）理论计算了电离势（IP）、电子亲和势（EA）和激发能（EE）。在这项工作中，我们利用以前开发的双群的广义张量收缩计划，并扩展它，以进行张量收缩涉及非完全对称和奇数排名张量。几个近似的自旋自由和两个组件的哈密顿量也可以在此实现中访问。我们已经将这种方法应用于卤素一氧化物（XO，X= Cl，Br，I，At，Ts）物种，以评估其他一些最近的EOMCC实现的质量，其中自旋-轨道耦合的贡献已近似在不同程度上。此外，我们还研究了CH $_2$ IBr，CH $_2$ I $_2$和I $_2^-$的各种激发态（以及同种的单电子附着和脱离电子态），并与一种密切相关的多参考耦合团簇方法，即中间哈密顿Fock空间耦合团簇单、双（IHFS-CCSD）理论进行了比较.
A quantum chemical study from a molecular perspective: ionization and electron attachment energies for species often used to fabricate single-molecule junctions
准确测定嵌入分子结中的分子的最低电子附着（$EA$）和电离（$IP$）能量对于正确估计\emph{e.g.}、电流（$I$）或偏置（$V$）的幅度（其中$I-V$曲线表现出显著的非欧姆行为）是重要的。用于制备n型导电单分子结的几种典型分子的最低电子附着能和电离能的基准计算（4，4 '-联吡啶、1，4-二氰基苯和4，4'-二氰基-1，1 '-联苯）和p型导电（苯二硫醇，联苯二硫醇，己烷单硫醇，基于EOM-CCSD（equation-of-motion coupled-cluster singles and doubles）的量子化学方法，研究了正己二硫醇与正己二硫醇之间的相互作用。它们表明与目前分子运输方法中获得的结果存在显着差异。本研究强调，除了一个可靠的量子化学方法，基组比无处不在的双zeta设置用于运输计算更好的是必要的。后者对于正确地确定$EA$是特别关键的问题，这在不包括足够的扩散基函数的情况下是不可能的。主导分子轨道（MO）的空间分布是另一个重要的问题，本研究引起了人们的注意，因为它敏感地影响由于在电极中形成的图像电荷的MO-能量移动$Φ$。目前的结果不能证实电极之间中点的点状MO的常见假设，其实质上影响实际的$Φ$值。
Frozen Natural Orbitals based Equation-of-motion coupled-cluster singles, doubles and triples for Ionized, Double-Ionized, Electron Attached and Two-Electron Attached states
